If Trump drops North American trade deal, pickups made in Mexico would be subject to LBJ-era import duties

MEXICO CITY—While the Trump administration talks of new import tariffs, there is already one in place that would slam manufacturers of pickup trucks in Mexico if the U.S. scuttles the North American Free Trade Agreement.

Under the so-called Chicken Tax first imposed more than a half-century ago, the U.S. levies a 25% duty on all pickup trucks and some work vans produced outside the country. Trucks produced in Mexico by the likes of General Motors Co., Toyota Motor Corp. and Fiat Chrysler Automobiles NV have been exempt...